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PALEOCLIMATIC CHANGES DURING THE LAST 2.5Ma RECORDED IN THE KATHMANDU BASIN, CENTRAL nepal HIMALAYAS

地学前缘 2000年第S1期7卷 383-385页

The Kathmandu valley is an intermountain basin located at about 1300 and surounded by mountains around 2400m.Thick fluvio\|lacustrine sediments from late Pliocene to Quaternary are accumulated there under monsoon climate.We undertook palynological and sedimentological studies on 284\|m\|long drilled core that reaches the basement of the kathmandu basin,in order to clarify the paleoclimatic changes and their tectonic link with uplifting of the Himalayas..The core is lithologically divided into three members:sand predominant lower member (51m),slit and clay dominant middle member (182m) and organic silty clay predominant upper member (45m).We analyzed fossil pollens contained in muddy samples which were taken from the middle and upper member in every one meter interval.The pollen assemblage is characterized by predominance of \%Quercus,\%30%～80% of the all arboreal pollen.We inferred paleoclimatic changes on the basis of comparison between present vegetation and climate of Kathmandu valley and surrounded mountains and pollen diagram which we obtained.For the purpose of inference of paleoclimate,we used the following genera as climatic index:\%Pinus\% for cold climate, \%Quercus\% and \%Cyclobalanopsis\% for warm climate, Alnus for wet climate and Gramineae for dry climate.As the reference.we also examined amount of another eight genera,two family and all spores.The pollen diagram shows two pattern of paleoclimatic changes:oscillation pattern with seven times fluctuation of warm and cold climate in younger period (ca.115m in depth),and older less fluctuated pattern of warm climate.During the older period (209～215m in depth),one cold stage was recognized,and is characterized by predominance of Pinus and occurrence of Tsuga .

关键词： paleoclimate core pollen magnetostratigraphy the Kathmandu basin Central nepal Himalayas

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THRUST PACKAGES OF 1.68 Ga INDIAN SUPRA-CRUSTAL ROCKS IN THE MIOCENE SIWALIK BELT,CENTRAL nepal HIMALAYAS

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地学前缘 2000年第S1期7卷 64-66页

作者： Harutaka Sakai\+1,Yutaka Takigami\+2,B.N.Upreti\+3,D.P.Adhikary\+3[WT5,5”BX](1.Department of Earth Science,Kyushu University,Ropponmatsu,Fukuoka,810\|8560 Japan 2.Kanto Gakuen University,Ohta\|shi,Gunma,373\|8515 Japan 3.Department of Geology,Tri\|Chan

The Siwalik Belt is a frontal fold\|thrust belt of the Himalayas and composed of thick sequence of foreland basin sediments derived from the Himalayas during the last 15 to 17 million years.From this Miocene belt in the central nepal,we discovered exotic thrust packages of the Middle Proterozoic rocks,which has been regarded as the Siwalik Group or post\|collisional sediments correlatable with the Subathu or Murree Formation in India.The thrust belt,called the Bagmati Belt,is narrowly distributed in the Siwalik Belt,22km to the north of the Main Frontal Thrust (MFT or HFF) that is an active fault and considered to be the deformation front of the Himalayan orogen.The Main Boundary Thrust (MBT) which separates the Siwalik Belt from the Lesser Himalayan Belt runs 7km to the north of the thrust packages.Within the belt,tectonic slices of 400m to 1km in thickness are repeated three to five times due to thrusts,sandwiching a thin slice of the Siwalik beds.The thrust package consists of the pre\|Siwalik sedimetary rocks and sills of dolerite,and named as the Bagmati Group.The thickness is only about 800m due to tectonic repition by thrust,although the group has been considered to be a continuous sequence attaining 2200m in thickness.We divided the Bagmati Group into three formations,each of which shows an upward\|coarsening and thickening sequence of 200 to 350m in thickness.All sequence is composed of red\|brown orthoquartzite,pink quartzite,micaceous shale and thin sandstone interbed and rhythmite,mottled hematite and hematitic pisolite.We interpret that the Bagmati Group was deposited in shallow lacustrine and desert environments.

关键词： thrust package the Bagmati Group the Siwalik Belt Central nepal Himalaya

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Behavioral responses to spatial heterogeneity in endangered Ganges River dolphins(Platanista gangetica gangetica)

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Water Biology and Security 2022年第3期1卷 67-76页

作者： Shambhu Paudel John L.Koprowski Usha Thakuri Yukiko Sasaki-Yamamoto Shiro Kohshima School of Natural Resources and the Environment University of Arizona1064 East Lowell StreetTucsonAZ85721USA Tribhuvan University Institute of ForestryPost Box:43PokharaNepal Haub School of Environment and Natural Resources University of WyomingBim Kendall House804 E Fremont StLaramieWY82072USA Wildlife Research Center of Kyoto University 2-24 Tanaka-Sekiden-choSakyo-kuKyoto606-8203Japan

Globally,the threat of endangerment and extinction of small cetaceans was highlighted after the recent extinction of the Chinese River dolphin or Baiji(Lipotes vexillifer).Species with a small population size and a limited geographic range,such as Ganges River dolphins(GRD),are more vulnerable to extinction.The social and behavioral needs of cetaceans have been identified as potential factors increasing their vulnerability to human disturbance.However,little is known about how GRD adapt their behaviors and diel activity patterns to spatiotemporal variation.In this paper,we examined the underwater behavior of GRDs in nepal by collecting echolocation clicks from three spatially stratified habitats in the Sapta Koshi River system over a six-month period.Our research found that GRDs behave differently in response to spatial heterogeneity,indicating diverse environmental requirements for GRD persistence.Behavioral activity and duration varied across habitats but not across time of day,suggesting that GRD behaviors are likely to be regulated by habitat structure regardless of the time of day.However,GRD consistently exhibited nocturnal activity peaks even when diurnal activity varied substantially.This indicates that river dolphins may favor nocturnal refuges as a reaction to human disturbance in highly regulated rivers.Managing human disturbances in conjunction with habitat heterogeneity can improve the persistence of riverine cetaceans.Here,we document behavioral and ecological information pertaining to GRD,which is essential to the formation of river dolphin recovery plans that link ecological perspectives to planning and management.

关键词： Ganges river dolphin Behavior Acoustic Ecology nepal

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How Himalayan communities are changing cultivation practices in the context of climate change

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Regional Sustainability 2023年第4期4卷 378-389页

作者： Ashma SUBEDI Nani RAUT Smriti GURUNG Department of Environmental Science and Engineering Kathmandu UniversityDhulikhelKavre45200Nepal

Climate change can have significant impacts on crop yields and food security.This study assessed the linkages between climate change and crop yields to obtain a better understanding on the drivers of food security.The study was conducted in Pasagaun village of Lamjung District in nepal,where household surveys and focus group discussions(FGDs)were used to collect data including crop cultivation,irrigation facilities,and adaptation strategies.Moreover,climate data(temperature and precipitation)from 1992 to 2020 were collected from the Khudi Bazar meteorological station and crop yield data were obtained from the Agri-Business Promotion and Statistics Division.Trend analysis of temperature and precipitation was conducted using MannKendall trend test and Sen’s slope method,and the results showed an increase in the average temperature of approximately 0.02℃/a and a decrease in the annual precipitation of 9.84 mm/a.The cultivation of traditional varieties of rice and foxtail millet(Kaguno)has vanished.Although,there was no significant impact of the maximum temperature on the yield of rice and maize,the regression analysis revealed that there are negative relationships between rice yield and annual minimum temperature(r=-0.44),between millet yield and annual precipitation(r=-0.30),and between maize yield and annual minimum temperature(r=-0.31),as well as positive relationship between rice yield and annual precipitation(r=0.16).Moreover,average rice yield and millet yield have decreased by 27.0% and 57.0% in 2000-2020,respectively.Despite other reasons for the decrease in crop yield such as the lack of irrigation facilities,out-migration of farmer,and increased pest infestation,respondents have adopted adaptation strategies(for example,shifts in cultivation time and changes in crop types)to minimize the impacts of climate change.More investigation and community-based farming education are needed to understand and alleviate the harmful impacts of climate change on crop yield,as effective adaptation coping strategies are st

关键词： Climate change Crop yield Adaptation strategies Farming practices Food security nepal

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The international conference on mountain development in a context of global change with special focus on the Himalayas was held successfully in Kathmandu, nepal

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Journal of Geographical Sciences 2018年第10期28卷 1560-1560,F0003页

作者： XIN Liangjie LIU Linshan

The international conference on mountain development in a context of global change with special focus on the Himalayas was held in Kathmandu, nepal on April 21-26.

关键词： The international conference on mountain development in a context of global change with special focus on the Himalayas was held successfully in Kathmandu nepal

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Epidemiology of dengue virus infections in nepal, 2006-2019

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Infectious Diseases of Poverty 2021年第2期10卷 89-89页

作者： Komal Raj Rijal Bipin Adhikari Bindu Ghimire Binod Dhungel Uttam Raj Pyakurel Prakash Shah Anup Bastola Binod Lekhak Megha Raj Banjara Basu Dev Pandey Daniel MParker Prakash Ghimire Central Department of Microbiology Tribhuvan UniversityKirtipurKathmanduNepal 不详

Background:Dengue is one of the newest emerging diseases in nepal with increasing burden and geographic spread over the years.The main objective of this study was to explore the epidemiological patterns of dengue sinc... 详细信息

关键词： Dengue DENV Aedes aegypti Outbreak nepal Spatial epidemiology

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SLOPE INSTABILITY HAZARDS IN GRANITES OF THE LESSER HIMALAYAN EXAMPLE OF THE PALUNG GRANITE OF CENTRAL nepal

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地学前缘 2000年第S1期7卷 44-45页

作者： I. R. Humagain, K. Schetelig[WT5,5”BX](Department of Engineering Geology and Hydrogeology in Aachen University of Technology, Lochner Str. 4\|20, D\|52056 Aachen/Germany)

Granites are hard and sound rock at relatively fresh or unweathered condition. Steep rocky slopes are the characteristic features in the area occupied by granites of the Lesser Himalaya including Kathmandu nappe. Almost vertical to sometimes overhanging slopes in granites look stable in dry season, but the steeper slopes in the areas occupied by granitic rocks are metastable to unstable. The instabilities are related to: variation in texture and mineral composition of granite, nature and intensity of weathering (mechanical and chemical), altitude of the area, orientation of natural slope with reference to the predominant joint sets, quality of rock mass, stress release and activity of subsurface water during monsoon. The study is supposed to be an example for the study of the slope instabilities in the other part of the Himalaya occupied by granitic bodies.

关键词： granite instability hazard Lesser Himalaya Central nepal

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MAIN CENTRAL THRUST ZONE IN THE KATHMANDU AREA, CENTRAL nepal, AND ITS TECTONIC SIGNIFICANCE

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地学前缘 2000年第S1期7卷 46-47页

作者： Kazunori Arita 1, Akira Takasu 2, Megh Raj Dhital 3, Kamal Raj Regmi 1,3 , Lalu Prasad Paudel 3[WT5,5”BX](1 Division of Earth and Planetary Sciences, Graduate School of Science, Hokkaido University, Kita 10 Nishi 8, Kita\|ku, Sapporo 060\|08

The Himalaya, a fold\|and\|thrust belt in the northern margin of the Indian continent, is characterized by thrust tectoncis (Schelling and Arita, 1991). It consists mainly of three thrust\|bounded lithotectonic units: from south to north the Sub\|Himalayan imbricate zone, the Lesser Himalayan thrust package (LH) and the Higher Himalayan thrust sheet (HH) with the overlying Tethys Himalayan sequence. These units are separated by a series of propagated thrusts, i.e. from south to north the Himalayan Frontal Fault (HFF), Main Boundary Thrust (MBT) and Main Central Thrust (MCT). These thrusts are splays off of an underlying mid\|crustal subhorizontal d$B;D(Jollement (Main Detachmen Trust or Main Himalayan Thrust), and were propagated southward with time. Among these thrusts the MCT is most important intracrustal thrust in considering the geological evolution of the Himalaya, and is controversial regarding its location and nature. In western and eastern nepal the Higher Himalayan Crystalline sheet is thrust over the Lesser Himalayan rocks along the MCT. In the Kathmandu area of central nepal also the high\|grade rocks of the HH with the overlying Tethyan sediments covers southward the Lesser Himalayan rocks, and form the Kathmandu nappe. In the north of the Kathmandu nappe the Higher Himalayan crystallines are skirted by the Main Central Thrust zone (MCT zone) which consists of green and black phyllites with sporadic garnet snow\|ball garnet and calcareous schist associated with characteristic mylonitic augen gneiss. The southern margin of the nappe is bounded by the Mahabharat Thrust (MT: Stoecklin, 1990) with a narrow zone of the LH which is cut by the MBT. But the relationship of the MCT in the north and the MT in the south is disputable and important (Arita et al., 1997: Rai et al., 1998: Upreti and Le Fort, 1999), and in the margin of the Kathmandu nappe the MCT zone has not been confirmed.

关键词： main central thrust zone central nepal tectonic significance

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VALLEY SLOPE DEFORMATION BY INTERACTION OF MASS ROCK CREEP,TALUS CREEP AND RAPID LANDSLIDES ALONG THE KALI GANDAKI RIVER IN THE HIMALAYAS OF WESTERN nepal

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地学前缘 2000年第S1期7卷 447-448,439页

作者： Hellmut R. Voelk[WT5,5”BX](University of Heidelberg, Institute of Geography, 69120 Heidelberg, Germany)

In its upper and middle course, the Kali Gandaki river in Western nepal flows across the Himalayan ranges more or less following tectonic lineaments (NNE—SSW). In this paper we focus our attention on certain slope deformations along the valley flanks of the middle course, especially on very narrow sections of this large transverse valley. Although the valley experienced several Pleistocene periods of strong glaciations and the powerful river flowing through it currently ranks as the second largest in nepal we find a number of those amazing valley constrictions in the studied area which should not be ascribed to differences in rock resistance against erosion or to active tectonic control. It can best be explained by deep\|seated rock creep (Chigira,1992), a process which is frequently connected with landslides or rockfalls and must have developed during late Pleistocene and Holocene, i.e. since the valley was deglaciated. In order to prove this thesis we shall describe the situation by means of three case studies between the villages of Rukse (upstream) and Beni (downstream). Another fourth example of gravitational slope deformation described in this paper is located downstream of the reach of previous valley glaciations. Here, too, deep\|seated rock creep is considered to be responsible for the observed mass movements and thus for slope deformation.

关键词： landslide deformation valley Kali Gandaki river Western nepal

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LOW TEMPERATURE DATING OF HIGH MOUNTAIN ROCKS:(U-Th)/He AGES FROM HIGHER HIMALAYAN SAMPLES, EASTERN nepal

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地学前缘 2000年第S1期7卷 16-17页

作者： Mary Hubbard 1, Martha House 2(1 Dept. of Geology, Thompson Hall, Kansas State University, Manhattan, KS 66506 USA 2 Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 USA)

Recently the (U\|Th)/He method on apatite has been applied to studies of cooling and exhumation in mountain belts in order to place constraints on the low temperature cooling history (Wolf et al., 1997; House et al., 1998). Because the closure temperature of the method is 65～75℃, it provides useful information regarding the exhumation of rocks through the upper few kilometers of the earth’s crust. When the (U\|Th)/He method is coupled with methods such as 40 Ar/ 39 Ar with higher closure temperatures (210～500℃), a cooling history can be reconstructed over a wide range of temperatures. In eastern nepal, in the Dudh Kosi valley a suite of samples from the Main Central Thrust (MCT) to the middle of the Higher Himalayan section was previously dated using 40 Ar/ 39 Ar on K\|feldspar, biotite, muscovite, and hornblende (Hubbard and Harrison,1989). We have applied the (U\|Th)/He method to apatite from these same samples. The structurally highest site, Ngozumba, is in the middle to upper part of the Higher Himalaya in the Gokyo valley. At Ngozumba previous 40 Ar/ 39 Ar ages include: muscovite at (16 6±0 4)Ma (closure temperature (CT)350℃), biotite at (16 8±1 4)Ma (CT 300℃), and K\|feldspar at (15 5±1 8)Ma (CT 250℃).The apatite age for an augen gneiss from this location was (6 3±3 8)Ma suggesting slower cooling for that part of the range during the last 15Ma. Structurally below Ngozumba, in the MCT zone, 40 Ar/ 39 Ar ages include:(20 9±0 2)Ma for hornblende (CT 500℃), (12 0±0 2)Ma for muscovite, and (8 0±0 2)Ma for K\|feldspar (CT 220℃). The apatite age obtained for a biotite schist at this location was (4 6±0 2)Ma and is consistent with relatively constant cooling since 12Ma. In between the MCT and the Ngozumba site samples were collected near the settlement of Ghat that yielded anomalously young 40 Ar/ 39 Ar ages:(7 7±0 4)Ma for muscovite, (7 5±0 6)Ma for biotite, and (3 6±0 2)Ma for K\|feldspar (CT 210℃). The apatite age is consistent with these young ages at (0 8±0 1)Ma. Plausible explanations for the young ages at th

关键词： U\|Th)/He dating exhumation Himalaya nepal cooling history

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